Objectives: In the present study, the antimicrobial property of extracts obtained from leaves of A. nilotica was evaluated as the leaves of A. nilotica are traditionally useful for treating infectious diseases. Methods: The air-dried A. nilotica leaves were packed into a Soxhlet apparatus and were extracted sequentially with petroleum ether (PE), benzene (BZ), dichloromethane (DCM), chloroform (CF), ethanol (EA) and water (AQ). Three gram negative (Escherichia coli, Klebsiella pneumonia, Proteus mirabilis) and three gram positive (Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae) organisms were selected for determining the antimicrobial potency of extracts by using agar well diffusion method and minimum inhibitory concentration(MIC) was also determined for all the extracts. Results: The results indicated that the various extracts of this plant exhibited different extent of antimicrobial activities but the ethanol extract of A. nilotica showed a higher potency than the positive control kamamycin at higher concentration tested in agar well diffusion method. MIC values also have indicated that the ethanol extract was considered as good antimicrobial agents whereas benzene, dichloromethane and aqueous extracts as moderately active agents and petroleum ether as weakly active. The potency of ethanol could be due to the presence of enormous amount of flavonoids and phenolic compounds. Conclusion: Thus the crude ethanol extract of leaves of A. nilotica can be used as a potential source of natural antibiotics.